Friedrich Nietzsche was a 19th century German philologist and philosopher famous for declaring "God is dead" and suggesting that only a new manmade moral structure will allow human beings to reach their full potential. From a family of Lutheran ministers, he studied theology and the classics at the University of Bonn in 1864-65, and then, still in his 20s, was made a professor at the University of Leipzig. Nietzsche was influenced by the work of Arthur Schopenhauer, and in Leipzig he also struck up a friendship with composer Richard Wagner, who helped secure Nietzsche a professorship in Switzerland, at the University of Basel. His relationship with Wagner soured after 1876, and in 1879 Nietzsche lost his job after repeated bouts of ill health (or, perhaps, hypochondria). For the next ten years he was an itinerant intellectual, living simply in France, Switzerland and Italy and writing his most famous works, including Thus Spake Zarathustra (1885), Beyond Good and Evil (1886), A Genealogy of Morals (1887) and Ecce Homo (1888). Nietzsche had a mental breakdown in 1889 and was an invalid the rest of his life, cared for by his mother and his sister, Elisabeth. He gained fame during the last years of his life, but he didn't know it -- his sister guided his legacy and reportedly allowed people to come gawk at him. Nietzsche wasn't known so much for a philosophical system or theory, but his repudiation of traditional Judeo-Christian values was a great influence on 20th century existentialists, who explored his challenge to reconsider human values in a godless world. He was also influential in the arts, from the George Bernard Shaw play Man and Superman (1905) to the Richard Strauss composition Also Sprach Zarathustra (1896). His belief that humans could achieve fulfillment when the strong defeated the weak and embraced a "will to power" to create a race of Übermensch -- superman -- was also an influence on 20th century fascists like Adolf Hitler. As a result, Nietzsche's ideas were simplified and perverted for propaganda purposes; his reputation has since recovered and he is considered a major figure in modern philosophy.

Extra credit:

Although there are no certain medical records, many Friedrich Nietzsche experts think his mental breakdown was caused by syphilis.